Blade clamp assembly

ABSTRACT

A blade clamp assembly for retaining a rotary blade on the arbor of a rotary tool comprises a blade washer for engaging the blade to hold the blade on the arbor and a clamp assembly threaded into the arbor to clamp the blade washer against the blade. The clamp assembly includes a planetary gear system for transmitting torque applied to the clamp assembly to the blade washer, wherein the planetary gear system multiplies the torque transmitted to the blade washer so that the torque transmitted to the blade washer is greater than the torque applied to the clamp assembly.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a divisional of U.S. patent application Ser.No. 10/687,542, filed Oct. 16, 2003, which is a continuation-in-part ofU.S. patent application Ser. No. 10/368,286, filed Feb. 18, 2003, whichclaims benefit under 35 U.S.C. § 119(e) of U.S. Provisional ApplicationSer. Nos. 60/357,377 and 60/357,549 filed Feb. 15, 2002, and claims thebenefit under 35 U.S.C. § 119(e) of U.S. Provisional Application Ser.No. 60/418,967 filed Oct. 16, 2002. U.S. patent application Ser. No.10/368,286 and U.S. Provisional Application Ser. Nos. 60/357,377;60/357,549 and 60/418,967 are herein incorporated by reference in theirentirety.

FIELD OF THE INVENTION

The present invention generally relates to the field of rotary powertools employing rotary blades and including, but not limited to, radialarm saws, circular saws, miter saws, and table saws, and moreparticularly, to a blade clamp assembly for securing a rotary saw bladeto the arbor of a rotary power tool without the use of tools.

BACKGROUND OF THE INVENTION

Rotary power tools such as miter saws, circular saws, radial arm saws,table saws, and the like, employ a rotary blade or saw blade comprisinga generally circular, planar disk having cutting teeth that is spun by amotor to cut a workpiece. The rotary blade includes a central aperturethrough which the blade is clamped to the motor output drive shaft orarbor of the rotary power tool.

The process of removing and replacing a rotary blade is difficult andtime consuming. Because of the forces placed on the rotary blade duringthe cutting operation, the blade must be securely clamped to the arborof the rotary tool. Typically, the arbor of the rotary tool is providedwith a flange against which the inner surface of the rotary blade isplaced. A second flange is then placed against the outer surface of therotary blade, and an arbor bolt is threaded into a threaded hole in thearbor through apertures formed in the rotary blade and flanges. Thearbor is then held stationary (e.g., by engaging a pin with the motorshaft or using a specially designed tool) and a wrench is used totighten the arbor bolt within the threaded hole, clamping the rotaryblade between the flanges.

Consequently, it has long been desirable to provide a blade clampingassembly that allows rotary blades to be removed and replaced quicklywithout the use of tools such as wrenches or the like. However, toeliminate the use of tools, any such blade clamping assembly must becapable of multiplying the torque that a user is capable of applying byhand to providing sufficient axial or clamping force to the rotary bladeto adequately secure the blade to the arbor.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a blade clamp assemblyfor retaining a rotary blade on the arbor of a rotary tool. In exemplaryembodiments, the blade clamp assembly comprises a blade washer forengaging the blade to hold the blade on the arbor and a clamp assemblythreaded into the arbor to clamp the blade washer against the blade. Theclamp assembly includes a planetary gear system for transmitting torqueapplied to the clamp assembly to the blade washer, wherein the planetarygear system multiplies the torque transmitted to the blade washer sothat the torque transmitted to the blade washer is greater than thetorque applied to the clamp assembly. A lever may be extended from theclamp assembly for increasing the amount of torque applied to the clampassembly by the user.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory onlyand are not necessarily restrictive of the invention as claimed. Theaccompanying drawings, which are incorporated in and constitute a partof the specification, illustrate an embodiment of the invention andtogether with the general description, serve to explain the principlesof the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The numerous advantages of the present invention may be betterunderstood by those skilled in the art by reference to the accompanyingfigures in which:

FIG. 1 is an isometric view illustrating an exemplary rotary power toolemploying a blade clamp assembly in accordance with the presentinvention;

FIG. 2 is an isometric view illustrating a blade clamp assembly inaccordance with an exemplary embodiment of the present invention;

FIG. 3 is an exploded isometric view illustrating components of theblade clamp assembly shown in FIG. 2;

FIG. 4 is a cross-sectional side elevation view of the blade clampassembly shown in FIG. 2;

FIG. 5 is an isometric view illustrating a blade clamp assembly inaccordance with a second exemplary embodiment of the present invention;

FIG. 6 is an exploded isometric view illustrating components of theblade clamp assembly shown in FIG. 5; and

FIG. 7 is a cross-sectional side elevation view of the blade clampassembly shown in FIG. 2.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to the presently preferredembodiments of the invention, examples of which are illustrated in theaccompanying drawings.

Referring to FIG. 1, an exemplary rotary power tool 10 employing a bladeclamp assembly 100 in accordance with the present invention isdescribed. The rotary power tool 10, in this case a radial arm saw,includes a motor assembly 20 having an arbor 30 on which a rotary blade40 (a rotary saw blade is illustrated) may be mounted. The arbor 30 isprovided with a flange 50 (see FIGS. 8 and 10) against which the innersurface 60 of the rotary blade 40 is placed. The arbor is then heldstationary (e.g., by engaging a pin with the motor shaft or the like)while the blade clamp assembly 100 is threaded into a threaded hole 70formed within the arbor 20, clamping the rotary blade 40 against theflange 50. Preferably, the blade clamp assembly 100 multiplies thetorque that a user is capable of applying by hand to provide sufficientaxial or clamping force to the rotary blade 40 to adequately secure theblade 40 to the arbor 30. The blade clamp assembly 100 thus allows arotary blade 40 to be affixed to the arbor 30 of a rotary power tool 10,in particular to a rotary cutting tool such as a hand-held circular saw,a miter saw, a table saw, a radial arm saw, or the like, without the useof hand tools such as wrenches, which are typically required by priorart blade clamping assemblies. Preferably, the blade clamp assembly 100is well balanced and has minimal protruding surfaces.

FIGS. 1 through 7 illustrate blade clamp assemblies 100 in accordancewith exemplary embodiments of the present invention. In each embodiment,the blade clamp assembly 100 employs a planetary gear system 102 formultiplying the torque applied to clamp the rotary blade 40 to the arbor30 of a rotary power tool (e.g., rotary power tool 10 shown in FIG. 1).Preferably, the blade clamp assemblies 100 are suitable for use withrotary blades 40 commonly used in rotary power tools such as miter saws,hand held circular saws, radial arm saws, table saws, and the like,employing circular saw blades. Such circular saw blades typicallyinclude a planar disk having cutting teeth for cutting the material of awork piece and a central aperture through which the blade is clamped tothe arbor 30 of the rotary power tool 10. In the embodiments illustratedherein in FIG. 1, the rotary blade 40 shown comprises a circular sawblade 104 of the type having a plurality of cutting teeth 106 arrangedabout a planar disk 108. This saw blade 104 is exemplary of the types ofrotary blades 40 that may be used with the blade clamp assembly 100 ofthe present invention. Thus, the cutting teeth 106 and planar disc 106shown are also exemplary. Nevertheless, it will be appreciated by thoseof ordinary skill in the art that the present invention is not limitedto use with any particular rotary blade, and that saw blades suitablefor use by the present invention may employ a wide variety of cuttingteeth and disc designs depending on the shaping operation or cut to beperformed by the rotary tool.

In the exemplary embodiments shown in FIGS. 2 through 7, the blade clampassembly 100 comprises a keyed blade washer 110 for engaging the rotaryblade 40 to hold the blade 40 against the flange 50 and a clamp assembly112 threaded into the threaded hole 60 formed in the arbor 30 forclamping the blade washer 110 against the blade 40. The planetary gearsystem 102 contained within the clamp assembly 112 transmits torqueapplied to the clamp assembly 112 to the blade washer 110, multiplyingthe torque transmitted to the blade washer 110 so that the torquetransmitted to the blade washer 110 is greater than the torque appliedto the clamp assembly 112 by the user.

The clamp assembly 112 includes a body 114, a bolt assembly 116 retainedwithin the body 114, a planet gear assembly 102 including a plurality ofplanet gears 118 and a sun gear 120 contained within the body 114 (threeplanet gears are provided in the embodiments illustrated) and a cap 122.In the embodiments illustrated, the outer surface of the body 114includes a groove or channel 124 shaped to provide engagement betweenthe body 114 and the cap 122 via pins 126 inserted in apertures 128 inthe cap 122 so that the pins 126 slide in the groove 124 and retain thecap 122 to the body 114 while allowing the cap 122 to rotate withrespect to the body 114. However, those of ordinary skill in the artwill appreciate that the cap 122 may be secured to the body 114 in otherways without departing from the scope and spirit of the presentinvention. However, the securing method used should not unduly interferewith rotation of the cap 122 on the body, although some interference maybe desirable, such as frictional interference or the like, forpreventing unwanted movement of the cap 122.

The bolt assembly 116 is seated in the body 114 and includes an arborbolt 130 having threads 132. The arbor bolt 130 extends through anaperture 134 formed in the bottom 136 of the body 114 for coupling theblade clamp assembly 100 to the arbor 30 of the rotary power tool (e.g.,rotary power tool 10 FIG. 1). The planetary gear system 102 transmitstorque applied to the cap 122 to the bolt assembly 116 for threading thearbor bolt 130 into the threaded hole 60 formed in the arbor 30,multiplying the torque transmitted to the bolt assembly 116 so that thetorque transmitted to the arbor bolt 130 is greater than the torqueapplied to the cap 122. In exemplary embodiments, the rotary power tool10 may include a spring loaded locking pin (not shown) that, whendepressed by the user, engages a hole formed in the motor output driveshaft or arbor 30 of the rotary power tool 10 to lock the arbor 30 inplace. In this manner, the arbor 30 is prevented from spinning as thecap 122 is rotated by the user for tightening or loosening the bladeclamp assembly 100, thereby clamping the rotary blade 40 against theflange 50 of the arbor 30 or releasing the rotary blade 40 from theflange 50.

As shown in FIGS. 2 through 7, the outer surface 138 of the bottom 136of the body 114 is seated against the keyed surface 140 of the bladewasher 110. The keyed surface 140 of the blade washer 110 includes aplurality of ridges or keys 142 that are received in corresponding slots144 between keys 146 formed in the outer surface 138 of the bottom 136of the body 114 thereby interlocking the blade washer 110 and the body114 as the blade clamp assembly 100 is tightened against the rotaryblade 40. In this manner, seating of the keyed blade washer 110 againstthe rotary blade 40 secures the body 114 through the interaction of thekeys 142 formed in the keyed blade washer 110 with the slots 144 formedin the body 114.

In the embodiments illustrated, the planetary gear system 102 furtherincludes a ring gear 148 formed on the inner side surface 150 of thebody 114. The planet gears 118 of the planet gear assembly 102 orbitabout the sun gear 120 within the ring gear 148. In one embodiment,shown in FIGS. 2, 3 and 4, the bolt assembly 116 comprises a carrier 152which includes a plurality of circumferentially spaced pins 154 (threepins 154 are illustrated) on which the planet gears 118 rotate, whilethe sun gear 120 is fixedly attached to the cap 122. As the cap 122 isrotated by the user, the sun gear 120 rotates, turning the planet gears118 and rotating the carrier 152, which in turn rotates the arbor bolt130 for threading the arbor bolt 130 into the arbor 30. In the secondembodiment shown in FIGS. 5, 6 and 7, the cap 118 functions as thecarrier for the planet gears 118 and includes circumferentially spacedpins 156 on which the planetary gears 118 rotate. In this configuration,the sun gear 120 is fixedly attached to the carrier 152 which is in turnfixedly attached to the arbor bolt 130. As the cap 122 is rotated by theuser, the planet gears 118 are rotated turning the sun gear 120 androtating the carrier 152, which in turn rotates the arbor bolt 130 forthreading the arbor bolt 130 into the threaded hole 60 of the arbor 30.

In both embodiments, the gear teeth of the planet gears 118 are enmeshedbetween the gear teeth of the sun gear 120 and the gear teeth of thebody ring gear 148. Preferably, the planet gears 118 are rotationallyconnected to the pins 154 or 156 so that the planet gears 118 rotatewhile orbiting between the sun gear 120 and the body ring gear 148 whenthe cap 122 is rotated by the user. The planet gears 118 rotate andorbit, causing the bolt assembly 116 to rotate in the same direction asthe cap 122, though at a slower rate. In this manner, the arbor bolt130, which is threaded to the arbor 30, rotates when the cap 122 isrotated, compressing the rotary blade 40 between the keyed blade washer110 and the arbor flange 50 thereby securing the blade 40 to the arbor30. Alternately, when the cap 122 is rotated in the opposing direction,the bolt assembly 116 also rotates in the opposing direction, looseningthe arbor bolt 130 from the arbor and unclamping the rotary blade 40 sothat the blade 40 may be released from the arbor 30.

Preferably, the size and pitch of the gear teeth of the planet gears118, the sun gear 120 and the ring gear 148 are selected along with therespective diameters of the cap 122, the planet gears 118 and the bodyring gear 148 to provide the desired torque multiplication. However, itwill be appreciated by those of skill in the art that the presentinvention need not be limited to the configuration specificallydisclosed herein. For example, it is contemplated that additional layersof planet gears may be provided without departing from the scope andspirit of the present invention.

The planetary design of the present invention is capable of providing alarge torque advantage compared to a conventional hand-tightened arborbolt since the torque applied to the arbor bolt 130 by hand-tighteningthe cap 122 may be multiplied many times over that which is typicallyapplied by a user's hand. Those of ordinary skill in the art willappreciate that the torque magnification factor of the present inventionwill depend upon the size of the parts, pitch diameters chosen for theparts, and the like. In the case of a conventional rotary power tool,such as rotary power tool 10, or the like, for example, parts may bechosen for enabling a person of ordinary physical strength tohand-tighten the blade clamp assembly 100 sufficiently to provideadequate axial force for retaining the saw blade 40 against the flange50 of the arbor 30. This may be desirable because the human hand is nottypically capable of applying the needed torque for sufficientlytightening a conventional hex-head-type blade clamp assembly without theuse of hand tools, such as wrenches, or the like, to provide thenecessary additional mechanical advantage.

In embodiments of the present invention, the cap 122 further includes anextensible lever 160 for providing additional mechanical advantage fortightening the blade clamp assembly 100 onto the arbor 30. In theembodiment illustrated in FIGS. 1 through 7, the extensible lever 160 isslidably received in the cap 122 via a groove and rail assembly 162 andincludes a raised portion 164 suitable for being pushed by a user toextend the extensible lever 160 outward from the cap 122. In thismanner, the lever may be used to provide additional mechanical advantagefor tightening and loosening the blade clamp assembly 100 while stillproviding a balanced assembly clamping the rotary blade 40 against thearbor 30 as the blade 40 is spun. Although an extensible lever 160 isdescribed in the exemplary embodiments illustrated herein, those ofordinary skill in the art will appreciate that many other configurationsfor aiding in the rotation of the cap 122 may be provided withoutdeparting from the scope and intent of the present invention. Forexample, extensible levers 160 may be provided that pivot away from thecap 122, or rotate outward from the cap 122, or notches or ridges may beplaced about the exterior of the cap 122 for providing friction againsta tightening or loosening force applied by the fingers of an operator.

In accordance with an exemplary embodiment of the present invention, toinstall a rotary blade 40 onto the arbor 30 of the rotary power tool 10,the rotary blade 40 is first placed on the arbor 30 against the arborflange 50. The keyed blade washer 110 is then placed on the arbor 30against the rotary blade 40 with ridges or keys 142 facing outward awayfrom the blade 40. The arbor bolt 130 of the clamp assembly 112 is nextthreaded into the threaded hole 60 of the arbor 30 and the clampassembly 112 is spun on until the arbor bolt 130 is hand tight. As thespinning body 114 of the clamp assembly 112 advances against the keyedblade washer 110 and the keys 142 and 146 of the washer 110 and the body114 mesh, the body 114 of the clamp assembly 112 stops rotating. Thespindle lock (not shown) of the rotary power tool is then engaged toprevent rotation of the arbor 30. Next, the extensible lever 160 ismanually extended and used to rotate the cap 122, driving the cap 122about the center axis of the arbor bolt 130. The planetary gear system102 multiplies the torque applied to the lever 160, causing the threadof the arbor bolt 130 to advance into the threaded hole 60 formed in thearbor 30 and forcing the body 114 against the keyed blade washer 110which is in turn forced against the rotary blade 40 clamping the blade40 between the washer 110 and the flange 50 of the arbor 30. After theblade clamp assembly 100 is tightened, the extensible lever 160 is slidback into the cap 122. Removal of the blade clamp assembly 100 forreplacing the rotary blade 40 is accomplished by reversing this process.

It is believed that the present invention and many of its attendantadvantages will be understood by the foregoing description, and it willbe apparent that various changes may be made in the form, constructionand arrangement of the components thereof without departing from thescope and spirit of the invention or without sacrificing all of itsmaterial advantages. The form herein before described being merely anexplanatory embodiment thereof, it is the intention of the followingclaims to encompass and include such changes.

1. A blade clamp assembly for retaining a rotary blade on an arbor of arotary tool, comprising: a blade washer for engaging the blade to holdthe blade on the arbor; and a clamp assembly for being threaded into thearbor to clamp the blade washer against the blade, the clamp assemblyincluding a body and a planetary gear system for transmitting torqueapplied to the clamp assembly to the blade washer, wherein the bodyincludes a keyed bottom surface and the blade washer comprises a keyedupper surface for engaging the keyed bottom surface of the body, andwherein the planetary gear system multiplies the torque transmitted tothe blade washer so that the torque transmitted to the blade washer isgreater than the torque applied to the clamp assembly.
 2. The bladeclamp assembly as claimed in claim 1, wherein the clamp assembly furthercomprises: a body; a bolt assembly retained within the body, the boltassembly including a threaded bolt extending through the body for beingthreaded into the arbor and a sun gear; a planet gear engaged with thesun gear and the body for rotating the sun gear; and a cap coupled tothe body and engaging the planet gear, the cap being turned for drivingthe planet gear, wherein the planet gear rotates the sun gear forturning the bolt assembly.
 3. The blade clamp assembly as claimed inclaim 2, wherein the body includes a keyed bottom surface and the bladewasher comprises a keyed upper surface for engaging the keyed bottomsurface of the housing.
 4. The blade clamp assembly as claimed in claim2, wherein the body comprises a ring gear for engaging the planet gear.5. The blade clamp as claimed in claim 2, wherein the cap includes alever extendable from the cap for increasing the amount of torqueapplied to the cap.
 6. A rotary tool, comprising: a motor; an arborrotated by the motor for supporting a rotary blade; and a blade clampassembly for retaining a rotary blade on the arbor, the blade clampassembly including: a blade washer for engaging the blade to hold theblade on the arbor; and a clamp assembly for being threaded into thearbor to clamp the blade washer against the blade, the clamp assemblyincluding a planetary gear system for transmitting torque applied to theclamp assembly to the blade washer, wherein the blade clamp assemblyfurther comprises a lever extendable from the clamp assembly forincreasing the amount of torque to the clamp assembly, the lever movablefrom a first position to a second position where the lever extendsoutwardly from the clamp assembly in the second position; and whereinthe planetary gear system multiplies the torque transmitted to the bladewasher so that the torque transmitted to the blade washer is greaterthan the torque applied to the clamp assembly.
 7. The rotary tool asclaimed in claim 6, wherein the clamp assembly further comprises: abody; a bolt assembly retained within the body, the bolt assemblyincluding a threaded bolt extending through the body for being threadedinto the arbor and a sun gear; a planet gear engaged with the sun gearand the body for rotating the sun gear; and a cap coupled to the bodyand engaging the planet gear, the cap being turned for driving theplanet gear, wherein the planet gear rotates the sun gear for turningthe bolt assembly.
 8. The rotary tool as claimed in claim 7, wherein thebody includes a keyed bottom surface and the blade washer comprises akeyed upper surface for engaging the keyed bottom surface of thehousing.
 9. The rotary tool as claimed in claim 7, wherein the bodycomprises a ring gear for engaging the planet gear.
 10. The rotary toolas claimed in claim 7, wherein the cap includes a lever extendable fromthe cap for increasing the amount of torque applied to the cap.